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Abstract:

According to various embodiments, a tracheal tube ventilating device
includes a sealing portion near a distal end of the tube. The sealing
portion has an electroactive polymer configured to undergo a clinically
effective change in volume, thickness, or both upon application of an
electrical potential. Such a change in volume, thickness, or both enables
sealing of the device against an inner surface of a trachea while
permitting the free passage of ventilating gas through the tube. In
addition, at least one electrical conductor is coupled to the
electroactive polymer and is configured to apply the electrical
potential.

Claims:

1. A tracheal tube ventilating device comprising: a tubular body
configured to be inserted into the trachea of a patient, wherein a
sealing portion at or near a distal end of the tubular body comprises an
electroactive polymer configured to undergo a clinically effective change
in volume, thickness, or both upon application of an electrical potential
to seal against an inner surface of the trachea while permitting the free
passage of ventilating gas therethrough; and at least one electrical
conductor coupled to the electroactive polymer and configured to apply
the electrical potential.

2. The tracheal tube ventilating device of claim 1, wherein the
clinically effective change in volume, thickness, or both causes a change
in an outside diameter of the sealing portion, a change in an inside
diameter of the sealing portion, or a combination thereof.

3. The tracheal tube ventilating device of claim 2, wherein the outside
diameter undergoes a change of at least approximately 20% when the
electrical potential is applied to the electroactive polymer.

4. The tracheal tube ventilating device of claim 3, wherein the outside
diameter undergoes a change of at least approximately 30% when the
electrical potential is applied to the electroactive polymer.

5. The tracheal tube ventilating device of claim 2, wherein the outside
diameter undergoes a change sufficient to create an effective seal
against the inner surface of the trachea.

6. The tracheal tube ventilating device of claim 1, wherein the distal
end of the tubular body comprises the sealing portion and the sealing
portion comprises entirely electroactive polymer.

7. The tracheal tube ventilating device of claim 1, wherein the sealing
portion comprises a length of about 8 to 55 millimeters.

8. The tracheal tube ventilating device of claim 1, wherein the sealing
portion is located an anatomically relevant distance from the distal end
of the tubular body and the sealing portion comprises entirely
electroactive polymer.

9. The tracheal tube ventilating device of claim 1, wherein the distal
end of the tracheal tube comprises the sealing portion and an outer layer
of the electroactive polymer is disposed on the tubular body.

10. The tracheal tube ventilating device of claim 1, wherein the sealing
portion is located an anatomically relevant distance from the distal end
of the tubular body and an outer layer of the electroactive polymer is
disposed on the tubular body.

11. The tracheal tube ventilating device of claim 1, wherein the tubular
body is operatively connected to a ventilator.

12. The tracheal tube ventilating device of claim 1, wherein the
electroactive polymer is selected from the group consisting of
polypyrroles, polyanilines, polythiphenes, polyethylenedisoxythiophenes
and mixtures thereof.

13. The tracheal tube ventilating device of claim 1, wherein the
clinically effective change in volume, thickness or both is at least
approximately 20%.

14. The tracheal tube ventilating device of claim 13, wherein the
clinically effective change in volume, thickness or both is at least
approximately 30%.

15. The tracheal tube ventilating device of claim 1, wherein the electric
potential is about 1 to 2 volts.

16. The tracheal tube ventilating device of claim 1, wherein the tubular
body comprises a first material; wherein the electroactive polymer
comprises a second material; and further comprising a transition region
joining the tubular body with the electroactive polymer.

17. The tracheal tube ventilating device of claim 1, further comprising a
lumen, wherein the at least one electrical conductor is disposed inside
the lumen.

18. A tracheal tube ventilating device comprising: a tubular body
configured to be inserted into the trachea of a patient, wherein a
sealing portion located an anatomically relevant distance from the distal
end of the tubular body comprises an electroactive polymer layer disposed
on the tubular body, wherein the electroactive polymer is configured to
undergo a clinically effective change in volume, thickness, or both upon
application of an electrical potential to seal against an inner surface
of the trachea while permitting the free passage of ventilating gas
therethrough; and at least one electrical conductor coupled to the
electroactive polymer and configured to apply the electrical potential.

19. The tracheal tube ventilating device of claim 18, wherein the
clinically effective change in volume, thickness, or both causes a change
in an outside diameter of the sealing portion.

20. The tracheal tube ventilating device of claim 19, wherein the outside
diameter undergoes a change of at least approximately 20% when the
electrical potential is applied to the electroactive polymer.

21. The tracheal tube ventilating device of claim 20, wherein the outside
diameter undergoes a change of at least approximately 30% when the
electrical potential is applied to the electroactive polymer.

22. The tracheal tube ventilating device of claim 19, wherein the outside
diameter undergoes a change sufficient to create an effective seal
against the inner surface of the trachea when the electrical potential is
applied to the electroactive polymer.

23. The tracheal tube ventilating device of claim 18, wherein the sealing
portion comprises a length of about 8 to 55 millimeters.

24. The tracheal tube ventilating device of claim 18, wherein the tubular
body is operatively connected to a ventilator.

25. The tracheal tube ventilating device of claim 18, wherein the
electroactive polymer is selected from the group consisting of
polypyrroles, polyanilines, polythiphenes, polyethylenedisoxythiophenes
and mixtures thereof.

26. The tracheal tube ventilating device of claim 18, wherein the
clinically effective change in volume, thickness or both is at least
approximately 20%.

27. The tracheal tube ventilating device of claim 26, wherein the
clinically effective change in volume, thickness or both is at least
approximately 30%.

28. The tracheal tube ventilating device of claim 18, wherein the
electric potential is about 1 to 2 volts.

29. The tracheal tube ventilating device of claim 18, further comprising
a lumen, wherein the at least one electrical conductor is disposed inside
the lumen.

30. A tracheal tube ventilating device comprising: a tubular body
configured to be inserted into the trachea of a patient, wherein a
sealing portion located an anatomically relevant distance from the distal
end of the tubular body comprises an electroactive polymer layer disposed
on the tubular body, wherein the electroactive polymer is configured to
undergo a clinically effective change in volume, thickness, or both of at
least approximately 20% upon application of an electrical potential to
seal against an inner surface of the trachea while permitting the free
passage of ventilating gas therethrough; at least one electrical
conductor coupled to the electroactive polymer and configured to apply
the electrical potential; wherein the clinically effective change in
volume, thickness, or both causes a change in an outside diameter of the
sealing portion sufficient to create an effective seal against the inner
surface of the trachea when the electrical potential is applied to the
electroactive polymer; wherein the sealing portion comprises a length of
about 8 to 55 millimeters; wherein the tubular body is operatively
connected to a ventilator; wherein the electroactive polymer is selected
from the group consisting of polypyrroles, polyanilines, polythiphenes,
polyethylenedisoxythiophenes and mixtures thereof; wherein the electric
potential is about 1 to 2 volts; and further comprising a lumen, wherein
the at least one electrical conductor is disposed inside the lumen.

Description:

BACKGROUND

[0001] The present disclosure relates generally to medical devices and,
more particularly, to airway devices, such as tracheal tubes.

[0002] This section is intended to introduce the reader to various aspects
of art that may be related to various aspects of the present disclosure,
which are described and/or claimed below. This discussion is believed to
be helpful in providing the reader with background information to
facilitate a better understanding of the various aspects of the present
disclosure. Accordingly, it should be understood that these statements
are to be read in this light, and not as admissions of prior art.

[0003] In the course of treating a patient, a tube or other medical device
may be used to control the flow of air, food, fluids, or other substances
into the patient. For example, medical devices, such as tracheal tubes,
may be used to control the flow of air or other gases through a trachea
of a patient. Such tracheal tubes may include endotracheal tubes (ETTs),
tracheotomy tubes, or transtracheal tubes. In many instances, it is
desirable to provide a seal between the outside of the tube or device and
the interior of the passage in which the tube or device is inserted. In
this way, substances can only flow through the passage via the tube or
other medical device, allowing a medical practitioner to maintain control
over the type and amount of substances flowing into and out of the
patient. In addition, a high-quality seal against the tracheal passageway
allows a ventilator to perform efficiently.

[0004] Generally, tracheal tubes are available in a range of sizes from
which doctors may select the closest approximate size for a particular
patient. The differences between tube sizes may generally reflect both
differences in the length of the tube as well as different tube
diameters. In particular, doctors may wish to select a tracheal tube with
an appropriate diameter in order to allow the tube to be easily inserted
into the patient while providing the largest possible airway path for
respiratory gases. For example, a tracheal tube with too small a tube
diameter may result in a high pressure drop during breathing or
ventilation. Conversely, a tracheal tube with too large a tube diameter
can become difficult to navigate through the larynx and trachea, possibly
increasing the time required to intubate the patient. In addition, a
large tracheal tube can prove somewhat uncomfortable for the patient. For
instance, irritation of the tracheal walls can result from increased
contact with the tracheal tube.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Advantages of the disclosed techniques may become apparent upon
reading the following detailed description and upon reference to the
drawings in which:

[0006] FIG. 1 is a perspective view of an exemplary ETT with a distal tip
comprising electroactive polymer (EAP) in an unexpanded state;

[0007]FIG. 2 is a perspective view of an exemplary ETT with a distal tip
comprising EAP in an expanded state;

[0008]FIG. 3 is a perspective view of an exemplary ETT with an EAP middle
section in an unexpanded state;

[0009]FIG. 4 is a perspective view of an exemplary ETT with an EAP middle
section in an expanded state;

[0010]FIG. 5 is a perspective view of an exemplary ETT with an outer
layer of EAP in an unexpanded state disposed on an outer surface of the
tube;

[0011]FIG. 6 is a perspective view of an exemplary ETT with an outer
layer of EAP in an expanded state disposed on an outer surface of the
tube;

[0012]FIG. 7 is a perspective view of an exemplary tracheostomy tube with
an EAP middle section in an unexpanded state;

[0013]FIG. 8 is a perspective view of an exemplary tracheostomy tube with
an EAP middle section in an expanded state;

[0014]FIG. 9 is a perspective view of an exemplary tracheostomy tube with
a distal tip comprising EAP in an expanded state; and

[0015] FIG. 10 is a perspective view of an exemplary tracheostomy tube
with an outer layer of EAP in an expanded state disposed on an outer
surface of the tube.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0016] One or more specific embodiments of the present techniques will be
described below. In an effort to provide a concise description of these
embodiments, not all features of an actual implementation are described
in the specification. It should be appreciated that in the development of
any such actual implementation, as in any engineering or design project,
numerous implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related and
business-related constraints, which may vary from one implementation to
another. Moreover, it should be appreciated that such a development
effort might be complex and time consuming, but would nevertheless be a
routine undertaking of design, fabrication, and manufacture for those of
ordinary skill having the benefit of this disclosure.

[0017] A tracheal tube ventilating device may be used to seal an airway of
a patient and provide positive pressure to the lungs when properly
positioned in a trachea. The ventilating gas passing through the tube
typically comprises air, but may also include anesthetic gases,
medications, or various gas mixtures, such as mixtures containing higher
concentrations of oxygen than atmospheric air. In addition, the source of
the ventilating gas is typically a medical device such as a ventilator.
During intubation or extubation, a clinician guides the tube through the
upper respiratory tract and past the vocal cords. This opening is
typically smaller than the inner diameter of the trachea. Thus, if
possible, an outer diameter of the tube is minimized during intubation or
extubation. Conversely, once the tube is properly positioned in the
trachea, the tube outer diameter is increased enough to create a seal
with the inner surface of the trachea. Finally, if possible, the tube
inner diameter may be increased to provide less resistance to the flow of
gas.

[0018] Electroactive polymers (EAP) are polymers having shapes that can be
modified when an electric potential is applied to them. EAPs are
generally divided into two categories: dielectric EAPs and ionic EAPs.
Activation of dielectric EAPs occurs when electrostatic forces are
created between two electrodes. The present techniques contemplate the
use of ionic EAPs, which require electric potentials of only a few volts
and electric currents in the range of a few microamps or milliamps,
making them ideally suited for use in humans. Moreover, many ionic EAPs
are biocompatible. Ionic EAPs swell and contract based on the movement of
ions and water molecules into or out of the polymer. Reversing or
removing the electric potential causes the ions and water molecules to
move in the opposite direction. Thus, these unique materials offer the
ability to control the size and/or shape of a portion of an ETT, as
described below. In addition, devices comprising EAP can configured in a
variety of ways to accomplish needed changes in volume, length, and/or
diameter of the tube or a portion of the tube.

[0019] An EAP may be selected that undergoes a clinically effective change
in volume, thickness, or both upon application of an electrical
potential. For example, an EAP may undergo a change in volume, thickness,
or both of at least approximately 20%. In other embodiments, the increase
may be at least approximately 30%. Using such an EAP in a tracheal tube
enables a tube to be designed that has a minimal outside diameter during
intubation or extubation and an increased outside diameter sufficient to
create a seal once properly positioned in the trachea. Using EAP provides
the clinician with the ability to adjust the outside diameter just enough
to create a proper seal. In addition, the inside diameter of the tube may
also be increased subsequent to intubation to ease the flow of gases
during patient ventilation. Further, as the outer walls of the tube may
contact the trachea over its length, the length of the seal may be
increased to provide improved sealing. Moreover, EAP will maintain its
shape or volume as long as the proper electrical potential is maintained.

[0020] Various non-limiting examples of embodiments of tracheal tubes
comprising EAP are disclosed below. For example, in certain embodiments,
an entire portion of the tracheal tube may comprise EAP. In other
embodiments, a layer of EAP may be disposed over the tube. Other
configurations are possible as well. Thus, the clinician has the
capability of adjusting the various dimensions of the tube to facilitate
intubation and extubation, maintain a proper seal, provide maximum
ventilation, and enhance patient comfort.

[0021] In certain embodiments, the disclosed tracheal tubes, systems, and
methods may be used in conjunction with any appropriate medical device,
including without limitation a feeding tube, an MT, a tracheotomy tube, a
circuit, an airway accessory, a connector, an adapter, a filter, a
humidifier, a nebulizer, nasal cannula, or a supraglottic mask/tube. The
present techniques may also be used to treat any patient benefiting from
mechanical ventilation, e.g., positive pressure ventilation. Further, the
devices and techniques provided herein may be used to treat human
patients, such as trauma victims, patients with tracheotomies,
anesthetized patients, cardiac arrest victims, patients suffering from
airway obstructions, and patients suffering from respiratory failure.

[0022] FIG. 1 is a perspective view of an embodiment of an ETT 10 with a
tip comprising an EAP in an unexpanded state. In the illustrated
embodiment, the ETT 10 comprises a tubular body 12. The tubular body 12
comprises a proximal end 18 and a distal end 20. In addition, the tubular
body 12 comprises a first material, a second material, and a transition
region joining the two materials. Specifically, in certain embodiments,
the first material used for the proximal end 18 of the tubular body 12
may be selected from materials commonly used for ETTs, such as polyvinyl
chloride (PVC). A transition 14 to the EAP tip begins near the middle or
distal end 20 of the tubular body 12. The transition 14 comprises a
region where the first material used for the proximal end 18 of the
tubular body 12 is gradually replaced by the EAP. In a presently
contemplated embodiment, the second material used for the EAP section 16
of the tubular body 12 comprises substantially all EAP and almost none of
the first material, although various mixtures of the materials that still
provide the desired shape-changing properties may be employed. Examples
of EAPs include, but are not limited to, polypyrroles, polyanilines,
polythiphenes, polyethylenedisoxythiophenes, or mixtures thereof. Such
EAPs are capable of undergoing a clinically effective change in volume,
thickness, or both upon application of an electrical potential. As the
second material used for the EAP section 16 may be less rigid than the
first material used for the rest of the tubular body 12, a tool such as a
stylet may be used to facilitate intubation. The transition 14 comprises
a proximal side 22 and a distal side 24. The distal side is positioned
towards the lower respiratory tract, while the proximal side is
oppositely oriented.

[0023] Other elements of the ETT 10 may include a suction lumen 26 to
remove secretions that may reside above the EAP section 16 during use.
Further, at least one electrical conductor 28 couples the EAP section 16
to a source of electrical potential. In certain embodiments, the
electrical conductor 28 may comprise a pair of insulated wires extending
from the source of electrical potential, passing through a lumen of the
tubular body 12, and emerging in the EAP as the bare ends of the wires,
or small terminal plates or electrodes. Examples of sources of electrical
potential include, but are not limited to, batteries, power supplies,
wall current, generators, etc. The electrical conductor 28 may comprise a
plug or other adaptor to enable it to be connected to the source of
electrical potential. In certain embodiments, the electrical potential
applied to the EAP may be between approximately 1 to 2 volts. Depending
on the EAP and the direction of electric current, the electrical
potential may act to expand or collapse the EAP.

[0024] Dimensions of the ETT 10 include an outside diameter 30 of the
tubular body 12 at the proximal end 18. In certain embodiments, the
outside diameter 30 at the proximal end 18 may be between approximately 2
and 16 mm. Further, the tubular body 12 near the proximal end 18
comprises an inside diameter 32. In certain embodiments, the inside
diameter 32 near the proximal end 18 may be between approximately 1.5 and
12 mm. Thus, a wall thickness 34 of the tubular body 12 may be between
approximately 0.5 to 2 mm. The EAP section 16 also comprises an
unexpanded outside diameter 36, an inside diameter 38, and an unexpanded
wall thickness 40. In certain embodiments, the dimensions of the EAP
section 16 when unexpanded may be substantially the same as the
dimensions of the proximal end 18 of the tubular body 12. Finally, the
EAP section 16 may comprise a length 42 configured to be long enough to
allow the EAP section 16 to create a sufficient seal against the trachea
wall. In certain embodiments, the EAP length 42 may be between
approximately 8 and 50 mm. The transition 14 may comprise a length 43
configured to be long enough to enable standard tube manufacturing
techniques to transition from the first material to the second material
in as short a distance as possible. In certain embodiments, the
transition length 43 may be between approximately 10 and 20 mm.

[0025]FIG. 2 is a perspective view of an embodiment of an ETT 10 with a
tip comprising an EAP in an expanded state. In the illustrated
embodiment, the expanded EAP section 16 comprises an outside diameter 44,
a wall thickness 46, and a length 48. In certain embodiments, the
expanded outside diameter 44 may be between approximately 8 and 55 mm.
For example, the expanded outside diameter 44 of the EAP section 16 may
be at least approximately 20% greater than the unexpanded diameter 36 of
the EAP section 16. In other embodiments, the increase may be at least
approximately 30%. The expanded outside diameter 44 is configured to be
large enough to allow the EAP section 16 to create an effective seal
against the trachea wall. In certain embodiments, the expanded wall
thickness 46 of the EAP section 16 may be between approximately 2 and 8
mm. Although most of the expansion of the EAP may be configured to
contribute to an increased wall thickness of the EAP section 16, there
may be some increase in the length of the EAP section as well. In certain
embodiments, the expanded length 48 of the EAP section 16 may be between
approximately 8 and 55 mm. In the particular embodiment shown, because
the transition 14 comprises some EAP, it may expand an amount less than
the EAP section 16. In addition, the inside diameter 38 of the EAP
section 16 remains the same in the expanded state, as substantially all
of the expansion of the EAP in this embodiment is directed outward. Other
elements shown in FIG. 2 in common with those shown in FIG. 1 are
discussed above.

[0026]FIG. 3 is a perspective view of an embodiment of an ETT 50 with an
EAP middle section 16 in an unexpanded state. In the illustrated
embodiment, because the EAP section 16 is in the middle of a tubular body
12, the body comprises two transition sections: a proximal transition 14
and a distal transition 51. The distal transition 51 comprises a proximal
side 53 and a distal side 54. In addition, the distal transition 51
comprises a length 56. In certain embodiments, the distal transition
length 56 may be the same as the proximal transition length 43, such as
between approximately 10 and 20 mm. The tubular body 12 comprises a
distal tip 52 that does not comprise EAP. Instead, the non-EAP distal tip
52 may be comprised of the same or similar materials as the proximal end
of the tubular body 12, such as, but not limited to PVC. The non-RAP
distal tip 52 comprises a length 58 that may be configured to be long
enough such that the EAP section 16 is located an anatomically relevant
distance from the distal end of the tubular body 12. In certain
embodiments, the length 58 of the non-EAP distal tip 52 may be between
approximately 3 and 20 mm. Other elements shown in FIG. 3 in common with
those shown in FIG. 1 are discussed above.

[0027]FIG. 4 is a perspective view of an embodiment of an ETT 50 with an
EAP middle section 16 in an expanded state. In the illustrated
embodiment, the expanded EAP section 16 comprises an outside diameter 60,
a wall thickness 62, and a length 64. In certain embodiments, the
expanded outside diameter 60 may be between approximately 8 and 55 mm.
For example, the expanded outside diameter 60 of the EAP section 16 may
be at least approximately 20% greater than the unexpanded diameter 36 of
the EAP section 16. In other embodiments, the increase may be at least
approximately 30%. The expanded outside diameter 60 is configured to be
large enough to allow the EAP section 16 to create an effective seal
against the trachea wall. In certain embodiments, the expanded wall
thickness 62 of the EAP section 16 may be between approximately 2 and 8
mm. Although most of the expansion of the EAP may be configured to
contribute to an increased wall thickness of the EAP section 16, there
may be some increase in the length of the EAP section as well. In certain
embodiments, the expanded length 64 of the EAP section 16 may be between
approximately 8 and 55 mm. In the particular embodiment shown, because
the proximal transition 14 and the distal transition 51 both comprise
some EAP, they may expand an amount less than the EAP section 16. In
addition, the inside diameter 38 of the EAP section 16 remains the same
in the expanded state, as substantially all of the expansion of the EAP
in this embodiment is directed outward. Other elements shown in FIG. 4 in
common with those shown in FIG. 3 are discussed above.

[0028]FIG. 5 is a perspective view of an embodiment of an ETT 66 with an
outer layer of EAP 68 in an unexpanded state disposed over the tubular
body 12. Such a configuration offers an alternative method of
construction compared to the ETTs discussed above, but still employs EAP
as the sealing material. In the illustrated embodiment, the EAP layer 68
comprises a thickness 70, configured to be small enough to enable the ETT
66 to be easily intubated or extubated. In certain embodiments, the
thickness 70 of the EAP layer 68 may be between approximately 0.5 to 1
mm. An interface 71 exists where the EAP layer 68 begins on the tubular
body 12. Other elements shown in FIG. 5 in common with those shown in
FIG. 1 are discussed above.

[0029]FIG. 6 is a perspective view of an embodiment of an ETT 66 with an
EAP layer 68 in an expanded state. In the illustrated embodiment, the
expanded EAP layer 68 comprises a wall thickness 72 and an outside
diameter 73. In certain embodiments, the expanded wall thickness 72 of
the EAP layer 68 may be between approximately 2 and 8 mm. As the
expansion of the EAP layer 68 inward is limited by the tubular body 12,
substantially all the growth is directed outward. In certain embodiments,
the expanded outside diameter 73 of the EAP layer 68 may be between
approximately 8 and 55 mm. For example, the expanded outside diameter 73
of the EAP layer 68 may be at least approximately 20% greater than the
unexpanded diameter 36 of the EAP layer 68. In other embodiments, the
increase may be at least approximately 30%. The expanded outside diameter
73 is configured to be large enough to allow the EAP layer 68 to create
an effective seal against the trachea wall. Other elements shown in FIG.
6 in common with those shown in FIG. 5 are discussed above.

[0030]FIG. 7 is a perspective view of an embodiment of a tracheostomy
tube 74 with an EAP middle section 82 in an unexpanded state. In the
illustrated embodiment, the tube 74 comprises a proximal end 76 and a
distal end 78. Because the EAP section 82 is in the middle of the tube
74, the tube comprises two transition sections: a proximal transition 80
and a distal transition 84. The proximal transition 80 comprises a length
81 and the distal transition comprises a length 85. In certain
embodiments, the proximal transition length 81 and the distal transition
length 85 may be the same, such as between approximately 10 and 20 mm.
The proximal transition 80 comprises a proximal side 88 and a distal side
90. Similarly, the distal transition 84 comprises a proximal side 92 and
a distal side 94. In addition, the EAP section 82 comprises a length 83.
In certain embodiments, the EAP length 83 may be between approximately 8
and 55 mm. The tube 74 comprises a distal tip 86 that does not comprise
EAP. Instead, the non-RAP distal tip 86 may be comprised of the same or
similar materials as the proximal end of the tube 74, such as, but not
limited to PVC. The non-EAP distal tip 86 comprises a length 87 that may
be configured to be long enough such that the EAP section 82 is located
an anatomically relevant distance from the distal end of the tube 74. In
certain embodiments, the length 87 of the non-EAP distal tip 86 may be
approximately 3 and 20 mm.

[0031] Other elements of the tube 74 include at least one electrical
conductor 96 that couples the EAP section 82 to a source of electrical
potential. In certain embodiments, the electrical potential applied to
the EAP may be between approximately 1 to 2 volts. Dimensions of the tube
74 near the proximal end 76 include an outside diameter 97, an inside
diameter 98, and a wall thickness 100. In certain embodiments, the
outside diameter 97 at the proximal end 18 may be between approximately 2
and 16 mm, the inside diameter 98 may be between approximately 1.5 and 12
mm, and the wall thickness 100 may be between approximately 0.5 and 2 mm.
The EAP section 82 also comprises an unexpanded outside diameter 102, an
inside diameter 103, and a wall thickness 104. In certain embodiments,
the dimensions of the EAP section 82 when unexpanded may be substantially
the same as the dimensions of the proximal end 76 of the tube 74. Other
features of the tube 74 analogous to ETTs are discussed above.

[0032]FIG. 8 is a perspective view of an embodiment of a tube 74 with an
EAP middle section 82 in an expanded state. In the illustrated
embodiment, the expanded EAP section 82 comprises an outside diameter
106, a wall thickness 108, and a length 110. In certain embodiments, the
expanded outside diameter 60 may be between approximately 8 and 55 mm.
For example, the expanded outside diameter 106 of the EAP section 82 may
be at least approximately 20% greater than the unexpanded diameter 102 of
the EAP section 82. In other embodiments, the increase may be at least
approximately 30%. The expanded outside diameter 106 is configured to be
large enough to allow the EAP section 82 to create an effective seal
against the trachea wall. In certain embodiments, the expanded wall
thickness 108 of the EAP section 82 may be between approximately 2 and 8
mm. Although most of the expansion of the EAP may be configured to
contribute to an increased wall thickness of the EAP section 82, there
may be some increase in the length of the EAP section as well. In certain
embodiments, the expanded length 110 of the EAP section 82 may be between
approximately 8 and 55 mm. In the particular embodiment shown, because
the proximal transition 80 and the distal transition 84 both comprise
some EAP, they may expand an amount less than the EAP section 82. In
addition, the inside diameter 103 of the EAP section 82 remains the same
in the expanded state, as substantially all of the expansion of the EAP
is directed outward. Other elements shown in FIG. 8 in common with those
shown in FIG. 7 are discussed above.

[0033]FIG. 9 is a perspective view of an embodiment of a tracheostomy
tube 111 with a tip comprising EAP 82 in an expanded state. In the
illustrated embodiment, the expanded EAP section 82 comprises an outside
diameter 112, an inside diameter 113, a wall thickness 114, and a length
115. Although similar in appearance to the expanded ETT shown in FIG. 2,
the EAP section 82 in FIG. 9 is configured to not only increase the
outside diameter 112, but also the inside diameter 113 in the expanded
state. An increased inside diameter may reduce the resistance of air
passing through the tube, increasing ventilation to the patient. This may
be accomplished by advantageous arrangement of the EAP material within
the EAP section 82. This feature may also be employed in the ETTs shown
in FIGS. 1-4 and the tracheostomy tubes shown in FIGS. 7 and 8 discussed
above. In certain embodiments, the expanded inside diameter 113 may be
between approximately 6 and 53 mm. In certain embodiments, the expanded
outside diameter 112 may be between approximately 8 and 55 mm, the
expanded wall thickness 114 may between approximately 2 and 8 mm, and the
expanded length 115 may be between approximately 8 and 55 mm. The
expanded outside diameter 112 is configured to be large enough to allow
the EAP section 82 to create an effective seal against the trachea wall.
Other elements shown in FIG. 9 in common with those shown in FIG. 7 are
discussed above.

[0034] FIG. 10 is a perspective view of an embodiment of a tracheostomy
tube 116 with an outer layer of EAP 82 in an expanded state disposed over
the tube. In the illustrated embodiment, an interface 118 exists where
the EAP layer 82 begins on the tube 116. In addition, the expanded EAP
section 82 comprises a wall thickness 120 and an outside diameter 122. In
certain embodiments, the expanded wall thickness 120 of the EAP layer 82
may be between approximately 2 and 8 mm. As the expansion of the EAP
layer 82 inward is limited by the tube 116, substantially all the growth
is directed outward. In certain embodiments, the expanded outside
diameter 122 of the EAP layer 82 may be between approximately 8 and 55
mm. For example, the expanded outside diameter 122 of the EAP layer 82
may be approximately 20% greater than the unexpanded diameter of the EAP
layer 82. In other embodiments, the increase may be at least
approximately 30%. The expanded outside diameter 122 is configured to be
large enough to allow the EAP layer 82 to create an effective seal
against the trachea wall. Other elements shown in FIG. 10 in common with
those shown in FIG. 7 are discussed above.